It seems to us that Earth stands quite stable(稳定的). But it is really m    all the time. It turns around a make-believe line through its centre. We c    this make-believe line Earth’s axis(轴). The t   ends of Earth’s axis are its poles. It t    Earth 24 hours to travel around its axis once. We look at the sun and say it ‘rises’ and travels across the sky, but the sun doesn’t really do s  . It is the turning of E    that makes us feel that the sun were moving across the sky. We can’t see the Earth is moving b    everything on Earth is turning around it.
As Earth moves around every 24 hours, the first half of Earth faces the sun and then the other h 8 . When our half of Earth is f 9  the sun, we say it is day. When our half is a    from the sun, we say it is night. It is the turning of Earth that tells us when to get up and when to go to bed.